Air curtain apparatus

ABSTRACT

An air curtain apparatus comprises a generally horizontal duct having at least one inlet and defining at least one outlet in a wall thereof. A plurality of axial fan units are mounted side-by-side across the at least one outlet defined in the wall of the duct, the axial fan units having rotational axes generally parallel to one another and side-by-side to blow air from an interior of the duct to an exterior of the duct. One or more grills are positioned adjacent to the axial fan units in a downstream flow path of the axial fan units, the grill(s) directing an air flow of the axial fan units into a downwardly directed air curtain. A method for creating an air curtain is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority on U.S. Provisional PatentApplication No. 62/504,161, filed on May 10, 2017.

FIELD OF THE APPLICATION

The present application relates to air curtain apparatuses of the typeused to create an air curtain transverse to a door to limit airinfiltration through the door.

BACKGROUND OF THE ART

Air curtains, also known as air doors, are conventionally used inindustrial or commercial installations in which relatively large doorsmust be occasionally opened and therefore result in heat or energylosses. An air curtain is a continuous wide stream of air that forms athermal barrier lessening heat loss through the open enclosure. Aircurtains may be used when doors are repeatedly open, for example in acommercial building with high occupancy. Air curtain apparatuses createan air curtain, i.e., a flow of air across the opened door to limitenergy loss to the exterior, whether it be heating energy loss or airconditioning energy loss.

Conventional air curtains use squirrel cage ventilators. However, suchsquirrel cage ventilators are relatively voluminous and heavy,difficultly scalable, whereby there is room for improvement.

SUMMARY OF THE APPLICATION

It is therefore an aim of the present invention to provide a novel aircurtain apparatus, addressing issues related to the prior art.

Therefore, in accordance with an embodiment of the present application,there is provided an air curtain apparatus comprising: a generallyupstanding duct having an upper inlet and a lower inlet; a plurality ofaxial fan units connected side-by-side to a wall of the duct, the axialfan units having rotational axes parallel to one another to blow airfrom an interior of the duct in a flow direction generally parallel torotational axes; and means to selectively close one of the inlets whileopening the other of the inlets.

In accordance with another embodiment of the present disclosure, thereis provided an air curtain apparatus comprising: a generally horizontalduct having at least one inlet and defining at least one outlet in awall thereof; a plurality of axial fan units mounted side-by-side acrossthe at least one outlet defined in the wall of the duct, the axial fanunits having rotational axes generally parallel to one another andside-by-side to blow air from an interior of the duct to an exterior ofthe duct; and at least one grill positioned adjacent to the axial fanunits in a downstream flow path of the axial fan units, the at least onegrill directing an air flow of the axial fan units into a downwardlydirected air curtain.

In accordance with yet another embodiment, there is provided a methodfor creating an air curtain comprising: collecting air in a duct;exposing the air in the duct to side-by-side axial fan units blowing theair out of the duct in a downward direction; exposing the air blowndownstream by the side-by-side axial fan units to at least one grilldirecting the air into forming an air curtain directed downwardly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, partly fragmented, of an air curtainapparatus in accordance with the present disclosure;

FIG. 2 is an enlarged fragmented perspective view of an axial fan unitof the air curtain apparatus of FIG. 1;

FIG. 3A is a schematic view showing a use of the air curtain apparatusof FIG. 1 in a vertical arrangement relative to a door with ceiling airin the operation;

FIG. 3B is a schematic view of the air curtain apparatus of FIG. 3A in afloor inlet operation;

FIG. 4 is a schematic view of the air curtain apparatus of FIG. 1 in ahorizontal arrangement;

FIG. 5 is a perspective view of an air curtain apparatus used as abooster in a ventilation system; and

FIG. 6 is a schematic view the air curtain apparatus of FIG. 1 in ahorizontal arrangement, with its air make-up unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and, more particularly, to FIGS. 1 and 2,there is shown an air curtain apparatus in accordance with the presentdisclosure at 10. The air curtain apparatus 10 is of the type that isused to create an air curtain in numerous different applications,especially in industrial and/or commercial settings, across closableopenings, such as entrance/exit sliding doors (FIGS. 3A and 3B) andgarage doors at reception docks or garages (FIGS. 1 and 4). Other usesare contemplated as well. For clarity and consistency, the expressionair curtain is used herein although such apparatuses may also be knownas air door, etc. The apparatus described herein is one that produces acontinuous wide stream of air that forms a thermal barrier lesseningheat loss through an open door or open enclosure.

Referring to FIGS. 1 and 2, the air curtain apparatus 10 is shown havingaxial fan units 20 supported by an integrated duct 30. The air curtainapparatus 10 may also comprise a supporting structure 40 (FIG. 4), atrigger switch 50 (FIGS. 3A and 3B), heating coils 60 and a thermostat70.

Referring to FIG. 1, the air curtain apparatus 10 is constituted ofmultiple side-by-side axial fan units 20, mounted to the integrated duct30, to form a self-supported upstanding structure. The axial fan units20 are arranged to be side-by-side and thus form a stack (FIG. 1) or rowof axial fans depending on the orientation of the air curtain apparatus10, the air curtain apparatus 10 being in a vertical orientation inFIG. 1. The air curtain apparatus 10 is said to be modular in that axialfan units 20 may readily be attached or detached from the air curtainapparatus 10 during manufacturing, to create air curtain apparatuses 10of different heights (in the vertical orientation) or different length(for horizontal use). Moreover, in an embodiment, the axial fan units 20are electrically wired so as to be independently powered (e.g., off the120V general supply), such that failure of one of the axial fan units 20does not cause a complete shutdown of the air curtain apparatus 10.Hence, the air curtain apparatus 10 has a redundancy for continuousoperation. The expression side-by-side may describe the fact that theaxial fan units 20 are in a parallel arrangement relative to oneanother, as opposed to being serially arranged in a duct.

Each of the axial fan units 20 is of the type having a square orrectangular housing 21 for a circular outlet 22. A fan 23 blows airthrough the outlet 22. The axial fan unit 20 is said to be axial in thatan axis of rotation of the fan 23 is generally parallel to a flowdirection out of the fan unit 20. The axis of rotation of the axial fanunit 20 is generally shown at X in FIG. 2, and this orientation isadvantageous in that the side-by-side arrangement of axial fan units 20is relatively compact compared to squirrel cages. The axial fan units 20may be direct drive or pulley-driven units. In the shown embodiments,the axial fan unit 20 have their respective fan axes generally parallelto one another (i.e., parallel, quasi-parallel, within 10 degrees ofbring parallel).

Referring to FIGS. 1 and 2, grills 24 cover the various outlets 22. Asshow in FIG. 2, a single grill 24 may be sized to cover multiple outlets22, but it is considered to provide one grill 24 per outlet 22.According to an embodiment, the grill 24 is double louvered (also knownas double louver grill or grille), with fixed vertical and horizontallouvers, to form a grid of square vents. The double louvered grill isarranged so as to direct the air flow in a direction substantiallyparallel to the rotational axis of the fans 23. Other arrangements areconsidered, such as a louvered grill, circular grill, etc. The aircurtain apparatus 10 must create a flow that is parallel to a plane ofan opening, and the axial fan units 20 are configured with the grills 24and oriented to give the air flow this parallel direction. Accordingly,the air curtain is created by the concurrent action of the multipleaxial fan units 20 all blowing air in the same direction. As analternative embodiment, the axial fan units 20 may be inside to buildpressure in the integrated duct 30, with the air exiting through thegrills 24 in a generally laminar stream as guided by the grills 24. Inan embodiment, the double louvered grill 24 defines square orrectangular vents having dimensions ranging from 0.375″ to 1.125″ (e.g.,0.5″×0.5″) in length and width, with a depth of at least 0.25″, tocreate the directional air flow.

Referring to FIG. 2, connection bars 25 may be used to align the axialfan units 20 in the side-by-side relationship shown. Other connectionarrangements are contemplated, for instance using the structuralintegrity of the housings 21 or of the integrated duct 30, among otherpossibilities.

The integrated duct 30 is typically made of sheet metal that forms apassage for air. The fan units 20 are directly mounted to an opening ina wall of the integrated duct 30, with necessary sealing to limit oravoid air leaks. Accordingly, the axial fan units 20 direct air from aninterior of the integrated duct to an exterior thereof. The integratedduct 30, when the air curtain apparatus 10 is used in a verticalconfiguration as in FIGS. 1, 2 and 3A/3B, may have a lower or floorinlet 31 having its own louver 31A and an upper or ceiling inlet 32 withits own louver 32A (FIGS. 3A and 3B). Although the expressions “floor”and “ceiling” are used, it is pointed out that the inlet 31 may bespaced from the floor and not directly on the floor and the ceilinginlet 32 may be spaced from the ceiling, not directly at the ceiling. Inother words, the floor inlet 31 is at an end of the integrated duct 30that is adjacent to the floor, whereas the ceiling inlet 32 is at an endof the integrated duct 30 that is adjacent to the ceiling. Moreover,although louvers are described, alternative components may be used, suchas traps, doors, flaps, covers. For instance, it is considered tomanually select and close/open the inlets with appropriate components.

The louvers 31A and 32A are selectively actuated based on the conditionsof operation. For instance, it is known that hot air has a lower densitythan cold air. In the winter months, the air curtain apparatus 10 mayclose the lower louver 31A and open the upper louver 32A to force warmerair into the integrated duct 30 as shown in FIG. 3A. In such winter use,hot air may be blown across the door to limit infiltration of cold air.Likewise, in summer months in which a dwelling is air-conditioned, thelower louver 31A may be opened while the upper louver 32A may be closedto force cold air across the opening of a door and thus prevent hot airinfiltration or cold air escape.

The operation of the louvers 31A and 32A may be commanded by thethermostat 70 that measures the outdoor temperature and thereforecontrols the louvers 31A and 32A as a function of the exteriortemperature. Considering that the doors are often closed, the triggerswitch 50 may determine when the air curtain apparatus 10 is to be used.The trigger switch 50 may be a position switch that automatically opensthe air curtain apparatus 10 when the door is opened, a limit switchthat is triggered by movement of a door, or an optical switch that viewsthe door opening.

Additional heat or cold may be provided by heating coils 60 located inthe air curtain apparatus 10. For example, the heating coils may beelectric coils, or may also refrigerant or coolant coils, or gas burnercoil, in which a fluid circulates for heat exchange with the air. It isalso considered to have coils of refrigerant from a refrigeration systempassing the air curtain apparatus 10 to condition the air before formingthe air curtain.

According to an embodiment, the various axial fan units 20 of the aircurtain apparatus 10 are independently connected to the power system,such that failure of one of the axial fan units 20 will not result in acomplete outage of the air curtain apparatus 10. The axial fan units 20may be controlled in speed by a common rheostat adjusting a powering ofthe axial fan units 20. In an embodiment, the axial fan units 20 may becalibrated to operate within a given decibel level.

Referring to FIG. 4, an alternative embodiment is shown, in which theair curtain apparatus 10 is oriented horizontally. In such a case, theremay be no need for an integrated duct 30, as the integrated duct 30 isparticularly useful to get inlet air at different locations, i.e., theground or the ceiling. It is however considered to provide the aircurtain apparatus 10 with a duct. Such a duct may bend to have a floorinlet for summer use, for example. The supporting structure 40 is usedto overhang the axial fan portion of the apparatus 10 above the opening.For example, the supporting structure 40 comprises chains supporting theaxial fan units 20 at a given distance from the ceiling (e.g., at least12″). The arrangement of FIG. 4 is particularly well suited to operatein winter, as the air curtain apparatus 10 supplies itself with warmerair mass that accumulates at the ceiling. Hence, the air curtainapparatus 10 may have access to sufficiently warm air to operate inwinter conditions without having to further heat the air. It is alsocontemplated to provide a heating coil(s) 60 in a duct of the aircurtain apparatus 10 as mounted horizontally as in FIG. 4.

Referring to FIG. 5, in accordance with another embodiment, a pluralityof the axial fan units 20 in the side-by-side arrangement are mounted toa ventilation duct 80 of the main ventilation system. An adaptor 81 maybe used depending on the shape of the ventilation duct 80. In such anarrangement, the axial fan units 20 act as a booster on the ventilationsystem to create the air curtain. It may be necessary to add othercomponents to the ventilation system considering the suction that willbe caused by the boosting, such as air intakes, louvers, automaticon/off switches, etc. In the embodiment of FIG. 5, the axial fans may bein the duct 80, with the double louvered grills 24 being surface mountedor being connected to the adaptor 81.

Referring to FIG. 6, in accordance with yet another embodiment, the aircurtain apparatuses 10 share a common dedicated ventilation systemincluding a rooftop air make-up unit 90. The air make-up unit 90 feedsoff outside air, and may have an integrated fan 91, to supply theintegrated duct with air pressure. The integrated fan 91 may be anyappropriate type of fan, such as a squirrel cage fan, or one or more ofthe axial fan units 20. The air make-up unit 90 may have a heatingcoil(s) 60. The air curtain apparatuses 10 then create the appropriateflow and curtain effect.

The air curtain apparatus 10 described herein may have differentcharacteristics in comparison to other air curtain systems, such asthose including squirrel cage fans. For example, the air curtainapparatus 10 of the present disclosure is more compact, lighter, and maybe less expensive, with an effective flow rate to energy consumptionrapport. The axial fan units 20 are capable of being subjected torelatively high levels of static pressure, enabling their use in thearrangement of FIG. 5, for example, in ventilation ducts 80, in aretrofit manner for example.

Therefore, the air curtain apparatus 10 operates a method for creatingan air curtain, by collecting air in a duct; exposing the air in theduct to side-by-side axial fan units blowing the air out of the duct ina downward direction; exposing the air blown downstream by theside-by-side axial fan units to at least one grill directing the airinto forming an air curtain directed downwardly. Collecting air in theduct includes inletting air from an air mass gathered proximal to andbelow a ceiling. Collecting air in the duct includes inletting airproximally to a floor. Inletting air proximally to the floor andinletting air from the air mass gathered proximal to and below theceiling are selected as a function of a temperature. Collecting air inthe duct includes collecting air from an existing ventilation system.Collecting air in the duct includes collecting air from a rooftopmake-up air unit. Exposing the air in the duct to side-by-side axial fanunits is performed when a door opening is detected.

1. An air curtain apparatus comprising: a generally horizontal ducthaving at least one inlet and defining at least one outlet in a wallthereof; a plurality of axial fan units mounted side-by-side across theat least one outlet defined in the wall of the duct, the axial fan unitshaving rotational axes generally parallel to one another andside-by-side to blow air from an interior of the duct to an exterior ofthe duct; and at least one grill positioned adjacent to the axial fanunits in a downstream flow path of the axial fan units, the at least onegrill directing an air flow of the axial fan units into a downwardlydirected air curtain.
 2. The air curtain apparatus according to claim 1,wherein the at least one inlet is open to a space proximal to theceiling.
 3. The air curtain apparatus according to claim 2, comprisingtwo of said inlet, with one said inlet being open to a space proximal tothe floor.
 4. The air curtain apparatus according to claim 3, furthercomprising automated louvers at each said inlet to selective open andclose access to the inlets.
 5. The air curtain apparatus according toclaim 4, further comprising at least one thermostat operativelyconnected to the automated louvers to control their operation.
 6. Theair curtain apparatus according to claim 1, wherein the at least oneinlet is connected to an existing ventilation system.
 7. The air curtainapparatus according to claim 1, wherein the at least one inlet isconnected to a dedicated rooftop make-up air unit.
 8. The air curtainapparatus according to claim 7, wherein the rooftop make-up air unit hasa heating coil.
 9. The air curtain apparatus according to claim 7,wherein the rooftop make-up air unit has at least one fan.
 10. The aircurtain apparatus according to claim 9, wherein the fan of the rooftopmake-up air unit is a squirrel cage fan.
 11. The air curtain apparatusaccording to claim 1, wherein the at least one grill is at least onedouble louver grill.
 12. The air curtain apparatus according to claim11, wherein a plurality of vents defined by the double louver grill eachhave a rectangular shape having a length ranging between 0.375″ and1.125″.
 13. The air curtain apparatus according to claim 12, wherein theplurality of vents defined by the double louver grill each have a widthranging between 0.375″ and 1.125″.
 14. The air curtain apparatusaccording to claim 12, wherein the plurality of vents defined by thedouble louver grill each have a depth of at least 0.25″.
 15. The aircurtain apparatus according to claim 1, comprising one of the at leastone grill for each said axial fan unit.
 16. The air curtain apparatusaccording to claim 1, wherein each of the plurality of axial fan unitsis connected independently to a powering system.
 17. The air curtainapparatus according to claim 1, further comprising a door sensordetermining an opening of at least one door associated with the aircurtain apparatus, the door sensor operatively connected to the axialfan units to control their operation as a function of the opening of theat least one door.
 18. The air curtain apparatus according to claim 1,comprising at least one heating coil in the duct. 19.-26. (canceled)